DE 10 2006 004 132 A1 describes an artificial foot with an elastic sole structure, extending from a heel region to a toe region, with a longitudinal axis, a connection to a below-knee part, an upwardly extending upper support structure and an elastic connection element arranged between the upper support structure and the sole structure. The upper support structure is, in the longitudinal direction, connected to the sole structure approximately in the approximately in the center of the foot by means of a coupling arrangement, which allows a relative tilt movement between the sole structure and the support structure. Here, the distance between the support structure and the sole structure in the center of the coupling arrangement remains constant, at least when loaded by weight when the patients are standing. The joint arrangement consists of an elastic polymer cylinder, which supports itself on the sole structure with a lower end face and on the lower side of the support structure with an upper end face. A pin arrangement complements the polymer cylinder and has spherical heads on both of its ends, which spherical heads support themselves firstly on the sole structure and secondly on the support structure and increase the stability of the connection. It is likewise possible for the joint arrangement in the form of a spherical cap to be formed with a correspondingly interacting ball socket in order thus to establish the tiltable connection between the support structure and the sole structure.
The artificial foot in accordance with the prior art renders it possible to improve the rollover action during walking; moreover, well defined statics in standing are present as a result of a forwardly displaced force transmission point. However, only small restoration forces can be realized by the elastic polymer cylinder, and so the spring properties of the artificial foot during walking have to be realized only by the sole structure. Moreover, as a result of the polymer cylinder, use is made of components susceptible to wear-and-tear, which is detrimental to the precision of the force transmission.